Dan F Posted November 20, 2023 Share Posted November 20, 2023 1 hour ago, yngndrw said: We have it all piped up with a mid-position valve to switch between cooling and heating I'm struggling to visualize what your setup looks like. Why do you need valves to switch from cooling to heating? Aren't you using a single Vaillant circuit for fan coils? Don't the fan coils need to run for both heating and cooling? Link to comment Share on other sites More sharing options...
yngndrw Posted November 21, 2023 Share Posted November 21, 2023 22 hours ago, Dan F said: I'm struggling to visualize what your setup looks like. Why do you need valves to switch from cooling to heating? Aren't you using a single Vaillant circuit for fan coils? Don't the fan coils need to run for both heating and cooling? The flow from the heat pump goes into a DHW priority diverter valve, then from the heating side of that into the heating/cooling mid-position valve. The heating side goes off to the radiators (Will be upgraded to underfloor heating after some building work) and the cooling side goes to the fan coil units. The reason that the heating and cooling is separate is due to condensation. The fan coil units are proper cooling ones with drain pans, so they can be run at a low temperature and remove some moisture from the air. Initially we were just going to use a diverter valve but we changed to a mid-position valve at the last minute so that we could use both the radiators/underfloor and the fan coil units for heating in order to boost efficiency. Right now the fan coils are not yet installed - That's a job for over Christmas. Link to comment Share on other sites More sharing options...
Dan F Posted November 21, 2023 Share Posted November 21, 2023 OK, kinda makes a bit more sense now. But I don't understand the motivation for doing this vs. using two separate Vaillant circuits and letting Vaillant control everything. Using two circuits gives you the flexibility to run each zone with its own controller, schedule, heat curve and flow temperature etc. Any specific motivation for trying to make one circuit service two circuits? On a separate note, do you have a buffer planned? Link to comment Share on other sites More sharing options...
yngndrw Posted November 21, 2023 Share Posted November 21, 2023 (edited) I'm not sure how that would work with two separate circuits, the heat pump can only serve one at a time (heating or cooling) so we are really just diverting. Our installer had never done cooling before so the cooling side was an experiment - It's essentially just a standard weather compensated heat pump setup with the cooling tacked on at the hip. We did try to minimise the amount of primary flow pipe before the heating/cooling mid-position valve in order to reduce the amount of pipe which would be susceptible to condensation. No buffer or hydraulic separation, we do have a volumiser on the return though. I can take a picture of the pipework this evening for better context. Edited November 21, 2023 by yngndrw Link to comment Share on other sites More sharing options...
yngndrw Posted November 21, 2023 Share Posted November 21, 2023 Pictures as promised: On the wider picture, flow and return from / to the heat pump in the bottom right. The blue diverter valve is for the DHW priority - Down goes to the cylinder. (It goes to the built-in coil and then onwards to a separate DHW charging plate heat exchanger) Above that diverter is the heating/cooling mid-position valve - Right is the cooling pipe which goes upstairs, left is the heating and goes both up and down. The volumiser is on the heating return behind the wall, under the stairs. A lot to fit into a tiny cupboard! Hope that helps to explain the context. Link to comment Share on other sites More sharing options...
Dan F Posted November 22, 2023 Share Posted November 22, 2023 (edited) > I'm not sure how that would work with two separate circuits, Two circuits mean that: - Everything can be controlled from Vaillant, no need for anything manual outside of Vaillant. - You can have two zones, with different target room temperatures. (this makes a lot of sense if, for example, you have radiators on the ground floor and fan coils on the first floor) - If required, you can have different heat curves and flow temperatures for each circuit too. If your radiators and fan coils are in the same rooms and you plan to use radiators for heating only and fan coils for cooling only, then I can see how your approach works and may be simpler. In our case, we have two circuits/zones; one for ground floor UFH (heating+cooling) and one for first floor MVHR post-heater (also heating+cooling). Each zone has its own controller (given it's two different areas in the house). Edited November 22, 2023 by Dan F Link to comment Share on other sites More sharing options...
yngndrw Posted November 22, 2023 Share Posted November 22, 2023 Oh I see, sorry when I mentioned manually enabling cooling I mean from within the Vaillant SensoComfort controls, not from something external. We don't have any zones, it's all on pure weather compensation with a steady-state curve - Room influence is fully disabled. (Except for a timed 18C setback temperature overnight) The property is one large zone. (It's an annexe so it's basically and upstairs and a downstairs room.) We didn't want any sub-zoning on the heating to maximise efficiency. (Typical Heat Geek setup basically) Pure weather compensation is working extremely well for the property, upstairs and downstairs are both very comfortable holding a constant 21-21.5C with a COP of 4.5 over the past month - Far better than expected without the underfloor heating. The curve is currently set to 0.5. It's worth noting that we only have the heat pump interface, we don't have the expansion unit so we only have those two MA1 and MA2 outputs - Was really hoping to be able to do it with just that unit. As I say it's all open-plan, so the idea is to put one fan coil downstairs in the kitchen (Supply duct will pull from the hallway so that it doesn't just pull greasy air through the fins) and the other will be upstairs in the bedroom. That should cover the entire property pretty well. So with that in mind, we want to retain a single zone across the property. I can see where the manual cooling mode option is in the Vaillant controls although haven't been able to test that because of the outside temperature limit they've set for some reason, the only thing we seem to be missing is the way to tell it that MA1 should be treated as a cooling zone output - I don't know if that should just automatically work? This is a diagram of the wiring - The heating/cooling mid-position valve is actually plumbed backwards to what you might normally expect, the A port goes to the fan coil units and the B port goes to the radiators: heat-pump-wiring.drawio.pdf Truth tables for the mid-position valve, this is how we have a switch controlling the two modes: If the white wire is connected to a permanent live and grey is connected to the cooling signal from the Heat Pump Interface: White | Grey | Output On | Off | Fan Coil Unit + Radiators (Heating) On | On | Fan Coil Unit (Cooling) If the white wire is also connected to the cooling signal from the Heat Pump Interface: Grey & White | Output Off | Radiators (Heating) On | Fan Coil Unit (Cooling) 1 Link to comment Share on other sites More sharing options...
davidh72 Posted June 15 Share Posted June 15 Did anyone ever get a better source for the 0020269259 resistor in the plug? I see some companies in the UK now charging over £400 for this 20p plug. I have talked to vaillant about the disgusting cost of this and my annoyance that I spent a lot of money on their ASHP and tanks etc and makes me wonder if all their equipment is this overpriced, but got no where with them. I am in Portugal next month was trying to buy there but it comes already in their ASHP as that part number is not in their spares catalogue so it only seems to be in Germany as an accessory but they will not post to UK and to Portugal they want 40 euros postage. Link to comment Share on other sites More sharing options...
yngndrw Posted June 15 Share Posted June 15 4 hours ago, davidh72 said: Did anyone ever get a better source for the 0020269259 resistor in the plug? I see some companies in the UK now charging over £400 for this 20p plug. I have talked to vaillant about the disgusting cost of this and my annoyance that I spent a lot of money on their ASHP and tanks etc and makes me wonder if all their equipment is this overpriced, but got no where with them. I am in Portugal next month was trying to buy there but it comes already in their ASHP as that part number is not in their spares catalogue so it only seems to be in Germany as an accessory but they will not post to UK and to Portugal they want 40 euros postage. This is the one we purchased, same item and works perfectly: https://www.theheatxchange.co.uk/vaillant-plug-coding-vai0020266328 Link to comment Share on other sites More sharing options...
Dave Jones Posted June 18 Share Posted June 18 we have cooling with fancoils. dont go too mad and overcomplicate it. IF your insulation and air tightness is good, running the ASHP running at dew point +1c (15-18) 24 x 7 through the underfloor and fancoils at virtually no cost keeps the house perfect. Extreme cooling is only needed for short blasts where heat has been allowed to build up which is a design failure. Link to comment Share on other sites More sharing options...
yngndrw Posted June 18 Share Posted June 18 If you do that, the fan coils won't provide any dehumidification for the house. That was one of the reasons we spent extra on installing proper fan coils with drains. We just have the cooling mode on a manual switch now, it has been working great and it removes a lot of moisture. Link to comment Share on other sites More sharing options...
JoeBano Posted June 25 Share Posted June 25 On 18/06/2024 at 07:10, Dave Jones said: we have cooling with fancoils. dont go too mad and overcomplicate it. IF your insulation and air tightness is good, running the ASHP running at dew point +1c (15-18) 24 x 7 through the underfloor and fancoils at virtually no cost keeps the house perfect. Extreme cooling is only needed for short blasts where heat has been allowed to build up which is a design failure. How’s your cooling been on dew point calculation today? Link to comment Share on other sites More sharing options...
Dave Jones Posted June 26 Share Posted June 26 (edited) 13 hours ago, JoeBano said: How’s your cooling been on dew point calculation today? well, the HA actually turned off the cooling as dew point rose to 18 (my rule is dew point +2) As the slab was still sitting at 19 i decided to run it at 12C flow temp for 2 hours just to see a worst case example. The unlagged pipework in plantroom (on the todo list) was dripping as was the underfloor manifold, at least the metal parts. BUT the fan coils were fantastically cool, basically aircon cool. The pipework feeding them is run through the pozi's which are stuffed full off insulation but im still worried about condensation on them. For the little extra cost id definitely pipe them fully insulated next time. After an hour you could feel the cool on the ground floor. was 30c outside and 21 in the house with bifolds open. I'm going to lag the manifold and supply pipework today and let it go all day at 12. Used 8 KWH of energy at the ASHP to provide the cooling, with 30 kwh of solar generated was free. Also let this 12c flow throught the MVHR intake cooling battery which has a built in condensation trap, not really sure how much of a difference it made really. Edited June 26 by Dave Jones 1 Link to comment Share on other sites More sharing options...
JohnMo Posted June 26 Share Posted June 26 40 minutes ago, Dave Jones said: and let it go all day at 12 I did that and found the floor was looking a matt colour, after 24 hrs, so just do it in 4hr blocks (2x a day) now so the floor surface temp doesn't fall below dew point. Link to comment Share on other sites More sharing options...
JoeBano Posted June 26 Share Posted June 26 I was running flow temperature 14c yesterday and had condensation issues on my fan coil units it kept my bedrooms at 21c, on day like yesterday and today I would expect them to hit 28c at night time. My house suffers massively with nighttime overheating. So they did work but I’m thinking I need to insulate my pipe work now. Link to comment Share on other sites More sharing options...
SteamyTea Posted June 26 Share Posted June 26 (edited) 5 hours ago, Dave Jones said: Used 8 kWh of energy at the ASHP to provide the cooling For a 9K temperature difference, so about 1 kWh/day.K. Though that was the extremes. Probably a smaller temperature difference over the full 24 hours. Not sure how large your house is, so cannot work out the kW/m2. Edited June 26 by SteamyTea Link to comment Share on other sites More sharing options...
Dave Jones Posted June 26 Share Posted June 26 3 hours ago, JoeBano said: I was running flow temperature 14c yesterday and had condensation issues on my fan coil units it kept my bedrooms at 21c, on day like yesterday and today I would expect them to hit 28c at night time. My house suffers massively with nighttime overheating. So they did work but I’m thinking I need to insulate my pipe work now. you will probably have to connect up the fan coils to a condensate drain as the heat exchanger will drip irrespective of the supply pipework. I'm going to have a ply with dehumidifiers as well to manually move the dew point inside the house to prevent it being an issue. Link to comment Share on other sites More sharing options...
yngndrw Posted June 26 Share Posted June 26 (edited) Ours has a constant stream of condensate running out of the drains, even with it running (And extracting moisture) for a while it doesn't stop. Indoor humidity rises to around 72% when it's off and drops to 57% when it's on. That's with keeping the indoor temperature at 22C. I'm not sure there's any way to get away from the condensate issue without drained fain coils. Edited June 26 by yngndrw 1 Link to comment Share on other sites More sharing options...
JoeBano Posted July 29 Share Posted July 29 I’ve had the cooling running all day at flow temperature 15c and my 3 myson Ivector’s have kept the bedrooms at 21c all day. It’s hit 30c and still is 27c outside temperature. No condensation on the pipe work inside humidity 48, downstairs has just hit 24.5c so I’m happy at the moment that I can get away with not insulating my pipe work. 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted July 30 Share Posted July 30 12 hours ago, JoeBano said: I’ve had the cooling running all day at flow temperature 15c and my 3 myson Ivector’s have kept the bedrooms at 21c all day. It’s hit 30c and still is 27c outside temperature. No condensation on the pipe work inside humidity 48, downstairs has just hit 24.5c so I’m happy at the moment that I can get away with not insulating my pipe work. interesting they look identical to the panasocin units. Same factory i wonder ? Link to comment Share on other sites More sharing options...
JohnMo Posted July 30 Share Posted July 30 20 minutes ago, Dave Jones said: interesting they look identical to the panasocin units. Same factory i wonder ? They are different, controller is completely different. Link to comment Share on other sites More sharing options...
Dave Jones Posted July 30 Share Posted July 30 there isnt really much of a controller on the panasonic ones, pretty much on and off. If you leave it on auto with a set temp it only turns on when there is flow from the ASHP. Link to comment Share on other sites More sharing options...
JohnMo Posted July 30 Share Posted July 30 4 hours ago, Dave Jones said: there isnt really much of a controller on the panasonic ones, pretty much on and off. If you leave it on auto with a set temp it only turns on when there is flow from the ASHP. The Myson one you can set different temperatures for different times if you need, plus you can alter the water flow for heating and cooling, above or below (cooling) the fan is activated. With temperature and time program if you set to night you set the Mac speed the fan runs during night hours. I have mine set to 23 all the time, and it tries to manage that room temp with the water it's given, warm or cool. 1 Link to comment Share on other sites More sharing options...
JoeBano Posted July 30 Share Posted July 30 Nice bit of kit can use third party controller to control temperature and fan speed but for £900 a pop they seem pricey! I managed to get 4 for £240 all in bargin of the year for me. Link to comment Share on other sites More sharing options...
JohnMo Posted July 30 Share Posted July 30 3 minutes ago, JoeBano said: managed to get 4 for £240 Real bargain, thought mine was cheap at £260 for one. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now